Numbers 35:23Or with any stone, with which a man may die, seeing him not, and cast it on him, that he die, and was not his enemy, neither sought his harm:Torrey's Topical Textbook

Deuteronomy 19:5As when a man goes into the wood with his neighbor to hew wood, and his hand fetches a stroke with the ax to cut down the tree, and the head slips from the helve, and lights on his neighbor, that he die; he shall flee to one of those cities, and live:Torrey's Topical Textbook